82 CLASS I.— ORDER II. 



ing ; stem simple, pinnated ; branches very long ; cells 

 very small, with a border entire ; ovaria inclining to 

 oval, and rather large ; colour deep brown ; size about 

 a decimetre. 



THREE TOOTHED. 



3. Sertularia tridentata. Base branching ; stem 

 straight and pinnated ; pinules diverging ; cells with 

 three teeth on their border, the opening oblique ; co- 

 lour yellowish ; height from four to six centimetres. 



Australasia. 



TAMARISK. 



4. Sertularia tamarisca. Cells tubular, with 

 three or four teeth on the border ; ovaria compressed 

 as if truncated, with a thorn at each side. 



Northern and Mediterranean seas, &c. 



fern. 



5. SERTULARiA^Z/cw/a. Stem flcxuous *, branches 

 articulated; cells tubular at the summit. 



European seas. 



TOOTHED. 



6. Sertularia dentata. Stem branching; cells 

 pyriform, with a toothed border ; ovaria oval, border 

 of the opening blackish ; height two centimetres. 



Bay of Cadiz. 



ELONGATED. 



7. Sertularia elongata. Base branching; stem 

 usually simple, pinnated, but rarely bipinnated ; 

 branches situate at the upper part of the stem ; cells 

 approximate, and small, with ciliated borders ; ovaria 

 oval, truncated at the summit, compressed, with two 



